“It is always a shock to people at studios that women do go see movies,” Nora Ephron said this spring.

Ephron, who passed away Tuesday at 71, and whose films included the beloved “Sleepless in Seattle” and “When Harry Met Sally,” knew a thing or two about making movies that women wanted to see. She also knew how hard it was to get them on the screen.

She was speaking at a screening of “This Is My Life,” the first film she directed, and mentioned that she hoped the huge success of “Bridesmaids,” which earned almost $170 million domestically last year, would mark the last time anyone would say that women don’t go to the movies. “But I promise you they are still saying it,” Ephron added. “It’s still frightening to them to not make something that is a tent pole with a possible sequel with a video game.”

Unfortunately, she was right. But Hollywood should be even more frightened of what will happen if it keeps taking female filmgoers for granted.

“Women have been left out, undervalued and marginalized in terms of the movies that are released and the way films are marketed,” says Hollywood.com analyst Paul Dergarabedian. Yet even while being ignored, women purchase half the movie tickets in the nation, according to the Motion Picture Association of America. Imagine the successes if there were more female characters onscreen than the 33 percent that appeared in the 100 top-grossing films in 2011. And imagine if more than 11 percent of those movies had female protagonists.